UNDERSTANDING TANDEM DOLLY: KEY FEATURES AND BENEFITS

07 Feb, 2025

Large-scale shipping of goods may be a difficult procedure requiring particular care to guarantee a safe arrival at the destination. Therefore, a dolly is a specialized piece of equipment used to carry large loads over long distances. In this article, Thaco Trailers provides detailed insights into the various types of dolly trailers and their advantages, helping businesses optimize their transportation processes effectively.

1. What is a Tandem Dolly?

A tandem dolly is a type of trailer hitch assembly used primarily in the transportation and logistics industry to connect and support multiple trailers in a line. It consists of a sturdy frame equipped with two axles (hence the term “tandem”) and a fifth-wheel coupling mechanism, which allows it to connect and haul an additional trailer behind the main one.

What is a Tandem Dolly?

2. Specifications of Tandem Dolly

A dolly may have various configurations, parts, and dimensions. The standard model of Thaco Trailers’ Tandem Dolly is designed and manufactured according to the following specifications:

General dimensions	Overall Length: 13’ 5’’ Overall Width: 96’’ Fifth Wheel Height: 48 ± 1’’ Rear Bolster Height: 39-3/8 ± 1’’ Drawbar Length: 104’’ (measured from the drawbar to the fifth wheel) Tandem Location: 53 1/2’’ (from the rear face of the bolster) Axle Spread: 49’’
Weight and Capacity	Tare Weight: 4,800 lbs (2,180 kg) ± 2% Gross Vehicle Weight Rating (GVWR): 44,000 lbs (20,000 kg)
Structural Components	Main Beam: Fabricated with GR80 steel, featuring 3/8’’ thick flange and 1/4’’ thick web Fifth Wheel: HOLLAND FW35 bolt-on type, ensuring a secure connection between trailers Drawbar: Fabricated using ASTM A-500 Grade B square tubes for durability Suspension System: HUTCH H9700 mechanical tandem suspension with Thaco Trailers’ high-arch leaf springs, ensuring a smooth and stable ride
Axles and Wheels	Axles: YORK 5” round axles with a 22,500 lbs capacity, optimized for handling heavy loads Wheels: ALCOA 22.5 x 8.25 hub-piloted aluminum wheels for strength and precision Tires: WESTLAKE 11R22.5-14PR tubeless tires, suitable for diverse terrains
Brake and Safety Systems	Brake System: SEALCO spring brake priority valve with WABCO ABS (2S/1M) for enhanced safety Safety Chain: 5/8’’ Grade 80 alloy steel chain for additional security
Additional Features	Electrical System: PHILLIPS sealed wiring harness with theft-resistant LED lights Lubrication: MOBILITH SHC 007 synthetic semi-fluid grease for smooth operation Painting: ED primer and powder topcoat with 7 years of warranty, meeting high durability standards

3. Advantages of Tandem Dolly

Tandem Dolly offers several advantages, making them the ideal choice for transportation businesses pursuing high operational performance and efficiency.

3.1 Increased Load Capacity

The Tandem Dolly allows the towing of another semi-trailer using a single tractor unit or a straight truck, effectively increasing the overall payload capacity without requiring additional vehicles, maximizing transportation efficiency, and reducing fleet operating costs.

3.2 Greater Traction and Control

Being equipped with high-quality WESTLAKE tubeless tires and a HUTCH H9700 mechanical tandem suspension system, the dolly ensures excellent traction and stability on various terrains, emphasizing the robustness of the system to enhance safety and control, especially when towing two trailers simultaneously.

3.3 Enhanced Maneuverability

The compact overall size of the dolly and the axle spacing improve the vehicle’s maneuverability, enabling easy handling within tight spaces with an additional trailer.

3.4 Reduced Wear and Tear

The advanced suspension system of the Tandem Dolly reduces the impact and stress on the chassis and axles, reducing the trailers’ maintenance costs specifically, and extending the service life of both the dolly and the towing vehicle in general. By minimizing vibrations and shocks on the road, the suspension system helps extend the lifespan of trailers and tow vehicles, reducing the need for repairs and the frequency of part replacements.

3.5 Compliance with Road Regulations

Tandem dollies can comply with road regulations in the U.S., Canada, and Australia due to their design and operational flexibility, which allow them to meet the specific regulatory requirements of each region.

Axle Weight Distribution: Tandem dollies distribute the weight of the trailer more evenly across multiple axles. This setup helps meet axle weight restrictions imposed by road authorities in each country, as it reduces the load on each axle, making it compliant with road regulations.
Compliance with Length and Combination Limits: In regions where multi-trailer combinations are allowed (such as Long Combination Vehicles in the U.S. and Canada or road trains in Australia), tandem dollies help comply with length restrictions. They enable safe and legal configuration of longer vehicle combinations while adhering to the maximum allowed length.
Adaptability to Weight Limits: Regulations often specify weight limits based on total gross weight or weight per axle. Tandem dollies are adaptable, allowing fleets to configure setups within the legal weight thresholds and reduce the likelihood of fines or penalties.
Braking Systems and Load Transfer: These dollies are typically equipped with braking systems that meet regional standards (such as FMVSS in the U.S., CMVSS in Canada, and ADR in Australia). Enhanced braking reduces stopping distances and ensures better control of the trailer load, which is critical for compliance with safety standards across all three markets.

3.6 Efficient Use of Fleet Resources

The Tandem Dolly allows transportation companies to optimize fleet costs by maximizing the utility of each tractor unit, reducing the number of vehicles required, lowering total fuel consumption, and thus enhancing overall operational efficiency. Although relatively small in terms of size, this addition to a fleet can drastically optimize a fleet business and even contribute to more sustainable logistics.

4. When do you need Tandem Dolly transport?

Transporting heavy loads: The Tandem Dolly is designed to handle heavy loads and distribute weight evenly across multiple axles, reducing the stress upon individual components. Therefore, it makes the perfect choice for hauling freights such as construction equipment, machinery, and other cargo that may exceed the standard payload limit of a single trailer. The connection for additional chassis per one tractor unit allows the vehicle to increase the total payload limit, reducing the number of trips required.

When do you need Tandem Dolly transport?

Hauling long or bulky items: the Tandem Dolly can improve load stability, increase the payload capacity, and thus enable the transportation of bulky goods without compromising maneuverability. It can also help a truck pull a straight trailer, allowing it to tow longer items than the main truck bed.

Supporting modular trailers: A Tandem Dolly is an essential device for modular or multi-trailer setups, allowing a truck to pull a semi-trailer in a straight line without the need for a specialized tractor. It also means that one tractor unit can tow multiple trailers as needed, improving flexibility and cost efficiency for the fleet operation.

Improving fuel efficiency: By allowing the combination of multiple trailers into one vehicle setup, a Tandem Dolly allows multiple trailers to be combined into one, consolidating loads and reducing the number of trips required, thereby enhancing overall fuel efficiency. Reduced fuel consumption can also help businesses minimize their environmental impact and contribute to sustainable logistics, which is especially beneficial for long-distance transport.

5. Safety Considerations for Tandem Dolly

5.1 Maintaining tandem dolly and using proper loading techniques

The Tandem Dolly needs regular maintenance, just like any other vehicle, to ensure optimal performance and safety. Proper maintenance and correct usage are crucial to prevent risks and ensure the longevity and reliability of the trailer. Key parts for regular inspections include brakes, tires, and coupling devices, all of which must be ensured to be in working order to remain safe for operation and meet legal requirements. Proper cargo loading is also crucial to the vehicle’s safety when transporting. Evenly distributing weight across the dolly’s axles help prevent shifting during transit and stabilizes the trailer, while improper balancing can lead to swaying and affect the vehicle’s balance. This ensures that the goods remain safe and minimizes the risk of spillage or damage to the products.

5.2 Consider weather for heavy hauling

Weather conditions during the trips can also significantly impact the dolly trailer’s safety. Rain, snow, ice, or precipitation can make it harder to control a loaded trailer. In adverse weather conditions, ensuring the responsiveness of braking systems, ABS functionality, proper tire pressure, and even weight distribution are crucial steps for safe driving. Proactive actions such as reducing driving speeds, increasing following distances, and careful route planning are also paramount when transporting heavy loads in unfavorable weather, while passive measures such as anti-skid devices and tire chains can provide additional safety, particularly in snow or icy conditions.

In addition to tire chains and anti-skid devices, ensuring that the Tandem Dolly is equipped with proper lighting systems, reflective markers, and warning signs can further enhance visibility and safety, especially in adverse weather conditions or nighttime transport. These measures help maintain vehicle control, particularly in challenging road conditions. Moreover, drivers should receive proper training on how to handle tandem dolly in various weather conditions to ensure they are well-prepared to deal with unexpected situations on the road.

6. Thaco Trailers offers high-quality tandem dolly to enhance your fleet’s efficiency.

Thaco Trailers’ Tandem Dolly is designed to the specifications as required according to the road and traffic regulations of the U.S., Canadian, and Australian markets. It includes safety features and redundancy of safety mechanisms. For instance, the Tandem Dolly is designed with a 5/8’’ Grade 80 alloy steel chain to provide backup connection to the fifth wheel assembly as required by Title 49 of the Code of Federal Regulations (CFR) and an Anti-lock Braking System (ABS) as required by the Federal Motor Vehicle Safety Standards (FMVSS) of the U.S., as well as other safety requirements from the Canadian National Safety Code (NSC) and the Australian Vehicle Standards Bulletins (VSB) and Australian Design Rules (ADRs).

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When prepared to investigate the premier tandem dolly that is available, consult Thaco Trailers. Our expert team is here to guide you through the selection process to ensure you find the perfect fit for your business. Contact our trailer specialists immediately to improve your operations with the necessary tandem dolly to advance your company.

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